1. Technical Field
The present invention relates to a method for manufacturing a semiconductor device. The invention also relates to heat treatment that can lower costs to manufacture a semiconductor device and can provide even and high performance of transistor elements.
2. Related Art
Examples of silicon recrystallization methods to recrystallize silicon that has been deposited on a substrate by a process such as chemical vapor deposition includes: solid-phase growth through high-temperature heat treatment at 800 to 1000 degrees Celsius; laser annealing through excimer laser radiation; and thermal plasma jet using thermal plasma as a heat source. JP-A-11-145148 and Crystallization of Si Thin Film Using Thermal Plasma Jet and Its Application to Thin-Film Transistor Fabrication (S. Higashi, AM-LCD '04 Technical Digest Papers, p. 179) are examples of related art.
The above-mentioned methods, however, have the following problems. The solid-phase growth involving heat treatment requires a semiconductor substrate used to sustain such high temperatures of 800 to 1000 degrees Celsius, that the substrate is practically limited to be made of quartz glass. However, it is economically difficult to manufacture a large substrate of expensive quartz glass. The laser annealing allows a silicon film to crystallize in an extremely short period of time, and is applicable to a wide variety of substrates even with poor heat resistance, such as glass or resin substrates. This method, however, requires high running costs and causes wide variation in element properties. The thermal plasma jet also allows a silicon film to crystallize in a short time, but consumes a lot of electricity for the heat source and a great amount of the rare gas argon (Ar), resulting in high costs.